SIX HIGH ROLLING MILL

LAMINOIR SEXTO

English Abstract

In a six high rolling mill comprising each pair
of upper and lower work rolls, intermediate rolls
and backup rolls, at least the intermediate rolls
among the work and intermediate rolls being adapted
for shifting in axial directions thereof, each of
the intermediate rolls has a barrel length longer
than that of the backup roll such that barrel ends
of the intermediate roll extend beyond barrel ends
of the backup roll at maximum and minimum shifted
positions of the intermediate roll, thereby
providing a six high rolling mill having a high mill
rigidity.

Claims

-78-


THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A six-high rolling mill for rolling steel sheet and having a vertical and
parallel rigidity
comprising: a pair of upper and lower work rolls, each rotatably mounted about
a parallel axis
in a common plane and defining therebetween a nip for said steel sheet to be
rolled
therebetween, a pair of upper and louver intermediate rolls, each rotatably
mounted about a
barrel center extending along a parallel longitudinal axis within said common
plane and
respectively backing said upper and lower work rolls, and a pair of upper and
lower backup
rolls, each rotatably mounted about a parallel axis within said common plane
and respectively
backing said upper and lower intermediate rolls, said intermediate and said
work rolls being
adapted for shifting in axial directions thereof, wherein each of the
intermediate rolls has a
barrel length longer than that of each of the backup rolls such that a barrel
end of each of the
intermediate rolls extends beyond a barrel end of each of the backup rolls
even after a
maximum and minimum axial shifting of each of the intermediate rolls, each of
said work
rolls provided with a like cylindrical roll profile, the upper and lower
intermediate rolls each
provided with a like roll crown profile in point symmetry relationship, said
roll crown profile
defined by a third order equation, which said equation determines that the
barrel length of
each intermediate roll is to be 1.2-2.5 times longer than that of each backup
roll, so that full
and continuous contact is maintained between said intermediate roll and said
work and
backup rolls so as to preserve mill rigidity, and to reduce sheet rolling
forces interacting
between said rolls, whereby a fluctuation of sheet crown and end thickness
inaccuracies such
as edge drop, meandering and ears are reduced,


wherein said third order equation of said lower intermediate roll is expressed
as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

where y: is the generating line that defines the roll crown profile;



-79-

where a: is a coefficient of the third order;

where b: is a coefficient of the first order;

x: is a coordinate of the lower intermediate roll barrel center relative to
the longitudinal axis
of the lower intermediate roll being coincidental with the x axis of an x-y
coordinate system,
the center point being at x=0, y=0 of the coordinate system,

where L: is 1/2 of the barrel length of the intermediate roll measured along
the x-coordinate;

where .delta.: is the axial shift amount of the intermediate roll along the
longitudinal axis relative
to the center point (0,0) of the coordinate system; and

where OF: is defined as the difference between the barrel length L and the
length LB, which
is half the backup roll barrel length; and

wherein the roll profile of the upper intermediate roll defined by a similar
third order equation
is in point symmetry relationship to the lower roll profile with respect to a
point thereon and
is expressed as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/ L).

2. The six high rolling mill claimed in claim 1, wherein the barrel length of
each work roll is
1.4-2.5 times as long as that of each backup roll.

3. The six high rolling mill claimed in claim 1, wherein each work roll has a
barrel diameter
in a range of 400-700 mm.

4. The six high rolling mill claimed in claim 1, wherein the barrel length of
each work roll is
not less than that of each intermediate roll.


-80-

5. A six high tolling mill for rolling steel sheet and having a vertical and
parallel rigidity
comprising: a pair of upper and lower work rolls, each rotatably mounted about
a parallel axis
in a common plane and defining therebetween a nip for each said steel sheet to
be rolled
therebetween, a pair of upper and lover intermediate rolls, each rotatably
mounted about a
barrel center extending along a parallel longitudinal axis within said common
plane and
respectively backing said upper and lower work rolls, and a pair of upper and
lower backup
rolls, each rotatably mounted about a parallel axis within said common plane
and respectively
backing said upper and lower intermediate rolls, said intermediate and said
work rolls being
adapted for shifting in axial directions thereof, whereto each of the
intermediate rolls has a
barrel length defined by a respective first and second barrel end, said
intermediate barrel
length longer than that of each of the backup rolls such that a barrel end of
each of the
intermediate rolls extends bc;yond a barrel end of each of the backup rolls
even after a
maximum and minimum axial shifting of each of the intermediate rolls, each of
said work
rolls provided with a like one-sided tapered roll profile, said one-sided
tapered profile defined
as a continuous taper from one of the barrel ends towards the other, the upper
and lower
intermediate rolls each provided witri a like roll crown in point symmetry
relationship, said
roll crown profile defined by a third order equation, which said equation
determines that the
barrel length of each intermediate roll is to be 1.2-2.5 times longer than
that of each backup
roll, so that full and continuous contact is maintained between said
intermediate roll and said
work and backup rolls so as to preserve mill rigidity, and to reduce sheet
rolling forces
interacting between said rolls, whereby a fluctuation of sheet crown and end
thickness
inaccuracies such as edge drop, meandering and ears are reduced,

wherein said third order equation of said lower intermediate roll is expressed
as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

where y: is the generating line that defines the roll crown profile;

where a: is a coefficient of the third order;



-81-

where b: is a coefficient of the first order;

where x: is a coordinate of the lower intermediate roll barrel center relative
to the longitudinal
axis of the lower intermediate roll being coincidental with the x axis of an x-
y coordinate
system, the center point being at the X=0, Y=0 of the coordinate system,

where L: is 1/2 of the barrel length of the intermediate roll measured along,
the x-coordinate;

where .delta.: is the axial shift amount of the intermediate roll along the
longitudinal axis relative
to the center point (0,0) of the coordinate system; and

where OF: is defined as the difference between the barrel length L and the
length LB, which
is half the backup roll barrel length; and

wherein the roll profile of the upper intermediate roll defined by a similar
third order equation
is in point symmetry relationship to the lower roll profile with respect to a
point thereon and
is expressed as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L).

6. A six high rolling mill for rolling steel sheet and having a vertical and
parallel rigidity
comprising: a pair of upper and lower work rolls, each rotatably mounted about
a parallel axis
in a common plane and defining therebetween a nip for said steel sheet to be
rolled
therebetween, a pair of upper and lower intermediate rolls, each rotatably
mounted about a
parallel and within said common plane and respectively backing said upper and
lower work
rolls, and a pair of upper ami lower backup rolls, each rotatably mounted
about a parallel axis
within said common plane and respectively backing said upper and lower
intermediate rolls,
said intermediate and said work rolls. being adapted for shifting in axial
directions thereof,
wherein each of the intermediate rolls has a barrel length defined by a
respective first and
second barrel and, said intermediate barrel length longer than that of each of
the backup rolls
such that one of said first and second barrel ends of each of the intermediate
rolls is always



-82-

relatively exterior to a barrel end of each of the backup rolls even after a
maximum and
minimum axial shifting of each of the intermediate rolls, the upper and lower
intermediate
rolls each provided with a like roll crown profile in point symmetry
relationship, said roll
crown profile defined by a third order equation, which said equation
determines that the
barrel length of each intermediate roll is to be 1.2-2.5 times longer than
that of each backup
roll, so that full and continuous contact is maintained between said
intermediate roll and said
work and backup rolls so as to preserve mill rigidity, and to reduce sheet
rolling forces
interacting between said rolls, whereby a fluctuation of sheet crown and end
thickness
inaccuracies such as edge drop, meandering and ears are reduced,

wherein said third order equation of said lower intermediate roll is expressed
as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

where y: is the generating line that defines the roll crown profile;

where a: is a coefficient of the third order;

where b: is a coefficient of the first order;

where x: is a coordinate of the lower intermediate roll barrel center relative
to the longitudinal
axis of the lower intermediate roll being coincidental with the x axis of an x-
y coordinate
system, the center point being at x=0, y=0 of the coordinate system;

where L: is 1/2 of the barrel length of the intermediate roll measured along
the x-coordinate;

where .delta.: is the axial shift amount of the intermediate roll along the
longitudinal axis relative
to the center point (0,0) of the coordinate system; and

where OF: is defined as the difference between the barrel length L and the
length LB, which
is half the backup roll barrel length; and



-83-

wherein the roll profile of the upper intermediate roll defined by a similar
third order equation
is in point symmetry relationship to the lower roll profile with respect to a
point thereon and
is expressed as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

7. A six high rolling mill for rolling steel sheet and having a vertical and
parallel rigidity
comprising: a pair of upper and lower work rolls, each rotatably mounted about
a parallel axis
in a common plane and defining therebetween a nip for said steel to be rolled
therebetween, a
pair of upper and lower intermediate rolls, each rotatably mounted about a
barrel center
extending along a parallel longitudinal axis within said common plane and
respectively
backing said upper and lower work rolls, and a pair of upper and lower backup
rolls, each
rotatably mounted about a parallel axis within said common plane and
respectively backing
said upper and lower intermediate rolls, the work rolls and intermediate rolls
being adapted
for shifting in axial directions thereof, wherein each of the intermediate
rolls has a barrel
length longer than that of each of the backup rolls such that a barrel end of
each of the
intermediate rolls extends beyond a barrel end of each of the backup rolls
even after a
maximum and minimum axial shifting of each of the intermediate rolls, each of
said work
rolls provided with a like two-sided taper roll profile, said profile defined
as a continuous
taper extending from a midpoint of t:he work roll barrel, outwardly towards
both of the barrel
ends, and the upper and lower intermediate rolls are each provided with a like
roll crown
profile in point symmetry relationship, said roll crown profile defined by a
third order
equation, which said equation determines that the barrel length of each
intermediate roll is to
be 1.2-2.5 times longer than. that of each backup roll so that full and
continuous contact is
maintained between said intermediate roll and said work and backup rolls so as
to preserve
mill rigidity and to reduce sheet rolling forces interacting between said
rolls, whereby a
fluctuation of sheet roll crown and end thickness inaccuracies such as edge
drop, meandering,
and ears, are reduced,

wherein said third order equation of said lower intermediate roll is expressed
as




-84-

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

where y: is the generating line that defines the roll crown profile;

where a: is a coefficient of tile third order;

where b: is a coefficient of the first order;

where x: is a coordinate of the lower intermediate roll barrel center relative
to the longitudinal
axis of the lower intermediate roll being coincidental with the x axis of an x-
y coordinate
system, the center point being at x=0, y=0 of the coordinate system;

where L: is 1/2 of the barrel length of the intermediate roll measured along
the x-coordinate;

where .delta.: is the axial shift amount of the intermediate roll along the
longitudinal axis relative
to the center point (0,0) of the coordinate system; and

where OF: is defined as the difference between the barrel length L and the
length LB, which
is half the backup roll barrel length; and

wherein the roll profile of the upper intermediate roll defined by a similar
third order equation
is in point symmetry relationship to the lower roll profile with respect to a
point thereon and
is expressed as

y1(x)=-a[{x-(.delta.+OF}/L]3+b(x/L)

8. The six high rolling mill claimed in claim 7, wherein the barrel length of
each work roll is
not less than that of each intermediate roll.




-85-

9. The six high rolling mill claimed in claim 7, wherein the barrel length of
each work roll is
1.4-2.5 times as long as that of each backup roll.

Description

-1-
2087156
Specification
SIX HIGH ROLLING MILL
Technical Field
This invention relates to a hot rolling mill, in
particular to a hot finish rolling mill for hot rolling
a sheet bar rolled by a rough rolling mill into a
thickness of a product, and to a six high rolling mill
for cold rolling strip sheet rolled by the hot finish
rolling mill, in particular, to precisely control a
sheet crown which is defined as a difference in the
sheet thickness between a central portion in sheet width
and portions in the vicinity of edges, thereby
preventing the sheet edges from extremely reducing to
thin thickness by edge drop.
Background art
Generally, when a hot rolled steel sheet is
produced by means of a hot finish rolling mill, rolls
axe deflected due to rolling load, thereby sheet thick-
ness at a central portion in sheet width becomes thicker
than sheet thickness at portions in the vicinity of
opposite edges of the rolled sheet, that is a sheet crown
is formed in the rolled sheet. Hy the way, the sheet
crown, if the sheet crown becomes large, makes it
difficult to provide an adequate sheet profile in cold
rolling in the next step, which also provides deficiency




_2_
in the shape and unavoidably results in reduction in
yield, so that it is required fox the hot finish rolling
mill to make the sheet crown as small as possible.
Thus, for a purpose of controlling the shape of
sheet to reduce the sheet crown, for example,
JP-A-62-10722 discloses a six high rolling mill to be
installed in a post-stage stand, wherein a rolling mill
array includes intermediate rolls having a constant
diameter over the full length thereof arranged between
backup rolls and work rolls, respectively, and these
intermediate rolls are adapted to shift in the mutually
opposite axial direction, thereby the ability to control
the sheet crown is enhanced. Furthermore, JP-A-5?-91807
discloses a rolling mill in which an S-shaped crown is
formed on any one of a work roll, an intermediate roll
or a backup roll, and the roll having the S-shaped crown
is shifted in the axial direction, thereby the ability
for controlling the sheet crown is enhanced.
However, in the former prior art disclosed in
JP-A-62-10722, the length of the intermediate roll is
made approximately the same as each length of the backup
roll and the work roll, so that when the intermediate
roll is shifted in order to make the sheet crown small,
the length of contact of the intermediate roll with the
backup roll and the work roll becomes short, and the
mill rigidity of the rolling mill decreases, and hence,




-3-
2087.56
inhere has been such a problem that when the rolling load
changes due to temperature deviation in the sheet bar or
the like, the roll gap between a pair of work rolls
greatly changes, and no predetermined accuracy in the
sheet thickness can be provided, and there has been such
a problem that when the center in sheet width deviates
from the center of the rolling mill due to deviation of
the sheet bar or the like, meanderings resulting from
the difference in rigidity of right and left portions of
the rolling mill take place, sometimes it is fallen into
impossibility of rolling from occurring of reduction
ears caused by miss rolling.
In addition, there has been such another problem
that spalling occurs on the surfaces of rolls resulting
from the increase in pressure between rolls on account
of the short length of contact of the intermediate roll,
and the service life of the rolls decrease.
It is noted that the problem mentioned above can
be avoided by decreasing the shift amount of the inter-
mediate rolls, but the ability for controlling the crown
of the work rolls in the rolling mill is greatly limited.
And also in the later prior art disclosed in
JP-A-57-91807, there has been such a problem, when the
profile control is performed by shifting intermediate
rolls provided with an S-shaped crown, the control of
crown becomes impossible due to the abrasion of rolls.




208~~5~
Furthermore, when the profile control is
performed by producing a curved roll crown on the inter-
mediate roll or the backup roll, it becomes necessary to
enlarge the roll crown in order to ensure a large control
amount for the crown, but when a sheet bar having a
relatively narrow width is rolled with small rolling
load by providing such a large roll crown, non-contact
portions are generated between the backup roll and the
intermediate roll or between the backup roll and the
work roll, and the mill rigidity of the rolling mill
becomes low, which unavoidably results in the decrease in
accuracy of the sheet thickness. In addition, there has
been another problem that when the non-contact portions
axe generated, meander and reduction ears occur in the
rolled sheet as a result of a difference of rigidity in
the axial direction of the rolls and as a result
sometimes rolling of sheet becomes impossible.
Disclosure of the Invention
This invention solves all such problems in the
prior art and provides a six high rolling mill adapted
for controlling both the sheet crown and edge drop of
sheet to prevent decrease in mill rigidity of the
rolling mill and meander of sheet resulting from the
great shifting of the intermediate roll and to attain
increase in service life of rolls.
A six high rolling mill according to the present




2087156
invention comprising pairs of upper and lower work
rolls, intermediate rolls and backup rolls, at least the
intermediate rolls among the intermediate and backup
rolls being adapted for shifting in mutually opposite
axial directions, wherein each of the intermediate rolls
has a barrel length longer than that of the backup roll
such that the opposite ends of the barrel of the
intermediate roll protrude beyond the opposite end of
the barrel of the backup roll still in the maximum and
minimum shifting positions of the intermediate roll, and
has a roll crown such that roll crowns of the pair of
the upper and lower intermediate rolls are in point
symmetry relationship.
In a preferred embodiment of the present
invention, the barrel length of the intermediate roll
may be 1. 22.5 times longer than that of the backup roll
and the barrel length of the work roll must be longer
than that of the intermediate roll and preferably
1. 42.5 times longer than that of the backup roll.
The shape of the roll crown in the intermediate
roll may be advantageously selected from S shape, one end
taper shape by which the barrel diameter is gradually
reduced toward one end of the roll barrel and opposite
ends taper shape by which the barrel diameter is
gradually reduced toward the opposite ends from the
center of the barrel length. The "S" shaped roll crown




_~_
2087156
may be defined by one pitch portion of a high order
curve formed by a high order function not lower than a
third order function, a since curve or approximate
curves of the high order curve or the sine curve.
The work roll may be provided with a roll crown
having a shape such as the one end taper shape defined
by that the barrel diameter is gradually reduced toward
one end of the roll barrel or the opposite ends taper
shape defined by that the barrel diameter is gradually
reduced toward the opposite ends from the center of the
barrel length. Such work rolls and the intermediate
rolls having one of the one end taper shaped roll crown
and the opposite ends taper shaped roll crown as
mentioned above may be appropriately combined to
constitute the six high rolling mill.
The six high rolling mill according to the
invention is able to reduce a load affected between
rolls, in particular, barrel end portions of the
intermediate and work rolls by providing the roll crown
for the intermediate rolls, thereby improving the
ability for controlling the crown. Particularly, the
"S" shaped roll crown can effectively reduce the rolling
load applied on the both edge portions of the sheet, and
when the intermediate roll are respectively shifted in
the ogposite directions relative to each other in the
spot symmetry relationship, the aforementioned function




-7-
2087156
is more remarkably attained and as a result a greater
crown control ability can be attained.
In the rolling mill according to the invention,
since the intermediate roll has a barrel length longer
than that of the backup roll as mentioned above, even if
the intermediate roll is greatly shifted, the
intermediate roll can always effectively contact the
backup roll ovex the full length thereof so that the
mill rigidity of the rolling mill is effectively
prevented from decreasing due to profile control,
therefore accuracy of the sheet thickness is greatly
improved without any affection caused by variation in
width of the sheet to be rolled. Furthermore, even if
the sheet to be rolled has camber, the sheet is
subjected to uniform reduction through the whole sheet
width so that occurring of meander can be effectively
reduced.
It should be noted that when the roll barrel of
the intermediate roll has a length as long as the roll
barrel of the backup roll, it is necessary to use a
large roll crown so as to provide a large difference
between the maximum diameter and minimum diameter of the
roll barrel of the intermediate roll in order to attain
a necessary crown control. As a result, a contact
pressure generated between rolls which are contacted
with each other in a line increases to occur spilling on


CA 02087156 2000-04-20
_ $ _
the surfaces of the rolls and also reduce the service
life of the rolls. Furthermore, when a sheet bar has a
relatively narrow width and a rolling load is small,
non-contact portions are generated between roll barrels
of the intermediate and backup rolls or between roll
barrels of the intermediate and work rolls. Thus, the
mill rigidity of the rolling mill reduces and as a
result , a necessary accuracy of the sheet thickness can
not be obtained. Therefore, in order to remove the
aforementioned problems, it is preferable that the
barrel length of th.e intermediate roll is 1. 22.5 times
as long as the back. roll.
FurthermorE~, the barrel length of the work roll
must be longer than that of the intermediate roll, and
preferably the barrel length of the work roll is
1. 42.5 times. as long as the backup roll so that the work
roll always e~ffect:Lvely contacts the intermediate roll
in spite of a shifi~ amount of the intermediate roll to
improve the mill rigidity of the rolling mill and
particularly reduce meandering of the sheet. Moreover,
the service :Lift o:E the roll is improved by increasing
the contact range 'between rolls and restraining the
contact pres:~ure between rolls from increasing.


CA 02087156 2000-04-20
- 8 (a) -


In a broad aspect, then, the present invention


relates to a six-high rolling mill for rolling steel


sheet and having a vertical and parallel rigidity


comprising: a pair of upper and lower work rolls,


each rotatably mounted about a parallel axis in a


common plane a.nd def=fining therebetween a nip for


said steel sheet to be rolled therebetween, a pair


of upper and lower intermediate rolls, each


rotatably mounted about a barrel center extending


along a parallel longitudinal axis within said


common plane and re:~pectively backing said upper and


lower work rolls, and a pair of upper and lower


backup rolls, each rotatably mounted about a


parallel axis within said common plane and


respectively backing said upper and lower


intermediate x-olls, said intermediate and said work


rolls being adapted for shifting in axial directions


thereof, wherein each of the intermediate rolls has


a barrel length longer than that of each of the


backup rolls ~~uch that a barrel end of each of the


intermediate r.-olls extends beyond a barrel end of


each of the backup :rolls even after a maximum and


minimum axial shifting of each of the intermediate


rolls, each oj= said work rolls provided with a like


cylindrical roll profile, the upper and lower


intermediate rolls each provided with a like roll


crown profile in point symmetry relationship, said


roll crown profile defined by a third order


equation, which said equation determines that the


barrel length of each intermediate roll is to be


1.2-2.5 times longer than that of each backup roll,


so that full <~nd continuous contact is maintained


between said :intermediate roll and said work and


backup rolls ao as to preserve mill rigidity, and to


reduce sheet :rolling forces interacting between said


rolls, whereby a fluctuation of sheet crown and end


thickness inaccuracies such as edge drop, meandering




CA 02087156 2000-04-20
- 8 (b) _
and ears are reduced, wherein said third order


equation of said lower intermediate roll is


expressed as


yl (x) =-a [ {x- (b+OF} /L] 3+b (x/L)


where y: is th.e generating line that defines the


roll crown profile; where a: is a coefficient of the


third order; where b: is a coefficient of the first


order; x: is a coordinate of the lower intermediate


roll barrel center relative to the longitudinal axis


of the lower intermediate roll being coincidental


with the x axis of an x-y coordinate system, the


center point ~~eing at x=0, y=0 of the coordinate


system, where L: is 1/2 of the barrel length of the


intermediate roll measured along the x-coordinate;


where b: is the axial shift amount of the


intermediate roll a=Long the longitudinal axis


relative to the center point (0,0) of the coordinate


system; and where OF: is defined as the difference


between the barrel .Length L and the length LB, which


is half the backup roll barrel length; and wherein


the roll profile of the upper intermediate roll


defined by a ~~imila_r third order equation is in


point symmetry relationship to the lower roll


profile with ~espect to a point thereon and is


expressed as


yl (x) =-a [ {x- (c5-+-OF} /L] 3+b (x/L) .


In another broad aspect, the present invention
relates to a :six high tolling mill for rolling steel
sheet and having a 'vertical and parallel rigidity
comprising: a pair of upper and lower work rolls,
each rotatabl~~r mounted about a parallel axis in a
common plane ~~nd defining therebetween a nip for
each said steel sheet to be rolled therebetween, a
pair of upper and lower intermediate rolls, each
rotatably mounted about a barrel center extending


CA 02087156 2000-04-20
- 8 (c) _
along a parallel longitudinal axis within said


common plane and re~;pectively backing said upper and


lower work rolls, and a pair of upper and lower


backup rolls, each rotatably mounted about a


parallel axis within said common plane and


respectively backing said upper and lower


intermediate rolls, said intermediate and said work


rolls being adapted for shifting in axial directions


thereof, whereto each of the intermediate rolls has


a barrel length defined by a respective first and


second barrel end, raid intermediate barrel length


longer than that of each of the backup rolls such


that a barrel end of. each of the intermediate rolls


extends beyond a baxrel end of each of the backup


rolls even after a maximum and minimum axial


shifting of e~:ch of the intermediate rolls, each of


said work rolls provided with a like one-sided


tapered roll profile, said one-sided tapered profile


defined as a continuous taper from one of the barrel


ends towards t:he other, the upper and lower


intermediate rolls each provided with a like roll


crown in point. symmE=try relationship, said roll


crown profile defined by a third order equation,


which said equation determines that the barrel


length of each rote=rmediate roll is to be 1.2-2.5


times longer than that of each backup roll, so that


full and continuous contact is maintained between


said intermeduate roll and said work and backup


rolls so as to preserve mill rigidity, and to reduce


sheet rolling forces interacting between said rolls,


whereby a fluctuation of sheet crown and end


thickness inaccuracies such as edge drop, meandering


and ears are .reduced, wherein said third order


equation of said lower intermediate roll is


expressed as


Yi (x) =-a (. ~x- (b-~-OF} /L] 3+b (x/L)




CA 02087156 2000-04-20
- 8 (d) -
where y: is the generating line that defines the


roll crown profile; where a: is a coefficient of the


third order; where b: is a coefficient of the first


order; where x: is a~ coordinate of the lower


intermediate roll barrel center relative to the


longitudinal axis of: the lower intermediate roll


being coincidental with the x axis of an x-y


coordinate system, t:he center point being at the


X=0, Y=0 of th.e coordinate system, where L: is 1/2


of the barrel length of the intermediate roll


measured along, the x-coordinate; where b: is the


axial shift amount of the intermediate roll along


the longitudir..al axis relative to the center point


(0,0) of the coordinate system; and where OF: is


defined as the difference between the barrel length


L and the length LB, which is half the backup roll


barrel length; and wherein the roll profile of the


upper intermediate roll defined by a similar third


order equation is in point symmetry relationship to


the lower roll. profule with respect to a point


thereon and i~~ expressed as


yl (x) =-a [ {x- (~+OF~ /L] 3+b (x/L) .


In yet another broad aspect, the present
invention rel~~tes to a six high rolling mill for
rolling steel sheet and having a vertical and
parallel rigidity comprising: a pair of upper and
lower work ro=_ls, e<~ch rotatably mounted about a
parallel axis in a common plane and defining
therebetween a nip :Eor said steel sheet to be rolled
therebetween, a pair of upper and lower intermediate
rolls, each rotatab:ly mounted about a parallel and
within said common plane and respectively backing
said upper anc~ lower work rolls, and a pair of upper
and lower bacJcup rolls, each rotatably mounted about
a parallel axis within said common plane and
respectively Jacking said upper and lower


CA 02087156 2000-04-20
- 8 (e) -
intermediate rolls, said intermediate and said work


rolls being adapted for shifting in axial directions


thereof, wherein each of the intermediate rolls has


a barrel length defined by a respective first and


second barrel and, ~~aid intermediate barrel length


longer than that of each of the backup rolls such


that one of said first and second barrel ends of


each of the intermediate rolls is always relatively


exterior to a barrel. end of each of the backup rolls


even after a maximum and minimum axial shifting of


each of the ir..termediate rolls, the upper and lower


intermediate rolls each provided with a like roll


crown profile in point symmetry relationship, said


roll crown profile defined by a third order


equation, which said equation determines that the


barrel length of each intermediate roll is to be


1.2-2.5 times longer than that of each backup roll,


so that full and continuous contact is maintained


between said intermediate roll and said work and


backup rolls :~o as t=o preserve mill rigidity, and to


reduce sheet x-olling forces interacting between said


rolls, whereb~~ a fluctuation of sheet crown and end


thickness inaccuracies such as edge drop, meandering


and ears are reduced, wherein said third order


equation of said lower intermediate roll is


expressed as


yl (x) =-a [ ~x- (~+OF} /L] 3+b (x/L)


where y: is the gene=_rating line that defines the


roll crown profile; where a: is a coefficient of the


third order; cohere '.o: is a coefficient of the first


order; where :~: is a coordinate of the lower


intermediate :roll barrel center relative to the


longitudinal axis of the lower intermediate roll


being coincidf~ntal 'with the x axis of an x-y


coordinate sy;~tem, the center point being at x=0,


y=0 of the cordinate system; where L: is 1/2 of the


barrel length of the intermediate roll measured




CA 02087156 2000-04-20
- 8 (f) _
along the x-coordinate; where ~: is the axial shift
amount of the intermediate roll along the
longitudinal axis relative to the center point (0,0)
of the coordinate system; and where OF: is defined
as the difference between the barrel length L and
the length LB, which is half the backup roll barrel
length; and wherein the roll profile of the upper
intermediate roll dE:fined by a similar third order
equation is in point. symmetry relationship to the
lower roll prc>file with respect to a point thereon
and is expres~;ed as
yl (x) =-a [ {x- (~+OF} /L] 3+b (x/L) .
In yet another broad aspect, the present


invention relates to a six high rolling mill for


rolling steel sheet and having a vertical and


parallel rigidity comprising: a pair of upper and


lower work ro~.ls, each rotatably mounted about a


parallel axis in a common plane and defining


therebetween ~i nip for said steel to be rolled


therebetween, a pair of upper and lower intermediate


rolls, each rotatab:Ly mounted about a barrel center


extending along a parallel longitudinal axis within


said common p=_ane and respectively backing said


upper and lower work rolls, and a pair of upper and


lower backup rolls, each rotatably mounted about a


parallel axis within said common plane and


respectively hacking said upper and lower


intermediate :=olls, the work rolls and intermediate


rolls being ac~.apted for shifting in axial directions


thereof, wherein each of the intermediate rolls has


a barrel leng!~h langer than that of each of the


backup rolls ;such that a barrel end of each of the


intermediate :rolls extends beyond a barrel end of


each of the b,~ckup rolls even after a maximum and


minimum axial shifting of each of the intermediate


rolls, each of said work rolls provided with a like




CA 02087156 2000-04-20
_ 8 (g) _
two-sided taper roll profile, said profile defined


as a continuous taper extending from a midpoint of


the work roll barre7_, outwardly towards both of the


barrel ends, a.nd the upper and lower intermediate


rolls are each. provided with a like roll crown


profile in point symmetry relationship, said roll


crown profile defined by a third order equation,


which said equation determines that the barrel


length of eacr. intermediate roll is to be 1.2-2.5


times longer than that of each backup roll so that


full and continuous contact is maintained between


said intermediate roll and said work and backup


rolls so as to preserve mill rigidity and to reduce


sheet rolling force: interacting between said rolls,


whereby a fluctuation of sheet roll crown and end


thickness inaccurac_Les such as edge drop, meandering,


and ears, are reduced, wherein said third order


equation of s~~id lower intermediate roll is


expressed as


yl (x) =-a [ {x- (~+OF} /L] 3+b (x/L)


where y: is the generating line that defines the


roll crown profile; where a: is a coefficient of the


third order; where b: is a coefficient of the first


order; where ~:: is a coordinate of the lower


intermediate xoll b<~rrel center relative to the


longitudinal ~ixis o:E the lower intermediate roll


being coincidental with the x axis of an x-y


coordinate sy:~tem, the center point being at x=0,


y=0 of the coordinal~e system; where L: is 1/2 of the


barrel length of thcs intermediate roll measured


along the x-coordinate; where b: is the axial shift


amount of the intermediate roll along the


longitudinal axis relative to the center point (0,0)


of the coordinate system; and where OF: is defined


as the difference between the barrel length L and


the length LB, whi.c:h is half the backup roll barrel




CA 02087156 2000-04-20
- 8 (h) -
length; and wherein the roll profile of the upper
intermediate roll de~f_ined by a similar third order
equation is in point: symmetry relationship to the
lower roll profile with respect to a point thereon
and is expressed as
yl (x) =-a [ (x- (b+OF} /L] 3+b (x/L) .
Brief Description of: the Drawings.
Fig. 1 is a schematic front view of a rolling
mill according to the present invention;




_g_
2087156
Fig. 2 is a diagrammatic view illustrating a
roll crown for an intermediate roll;
Fig. 3 is a schematic view illustrating the
intermediate rolls in shifted positions;
Fig. 4 is a block diagram of a control system of
the rolling mill;
Fig. 5 shows graphs showing a relationship
between the pressure between rolls and the sheet crown;
Fig. 6 is a graph showing a relationship between
ratio of barrel length of the intermediate and backup
rolls and the maximum pressure between rolls;
Fig. 7 is a graph showing contact conditions
between rolls with respect to the ratio of barrel length
of the intermediate and backup rolls;
Fig. 8 is a diagrammatic view illustrating a
bending of the intermediate roll;
Fig. 9 is a graph showing a relationship between
the ratio of barrel length of the intermediate and backup
rolls and the deflection amount of the intermediate roll;
Fig. 10 is a graph showing a dist'zibution of
sheet crown with respect to the number of rolled sheets;
Fig. 11 is a diagrammatic view illustrating a
supply of lubricant;
Fig. 12 is a diagrammatic view illustrating a
supply of lubricant;
Fig. 13 is a graph showing a relationship




-10-
2087~~ fi
between the diameter of the work roll and crown control
amount;
Fig. 14 is a schematic front view illustrating a
rolling mill;
Fig. 15 is a graph showing a distribution of
sheet crown with resgect to the number of rolled sheets;
Fig. 16 is a graph showing amount of occurred
edge drops;
Fig. 17 is a schematic front view illustrating a
rolling mill;
Fig. 18 is a diagrammatic view illustrating a
tapered portion of a roll;
Fig. 19 is a schematic view illustrating
intermediate rolls in shifted position;
Fig. 20 is a graph showing a distribution of
pressure between rolls;
Fig. 21 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 22 is a schematic front view illustrating a
rolling mill;
Fig. 23 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 24 is a schematic front view illustrating a
rolling mill;
Fig. 25 is a diagrammatic view illustrating a
tapered portion of a roll;




-11-
2087156
Fig. 26 is a schematic view illustrating
intermediate rolls in shifted position;
Fig. 27 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 28 is a schematic front view illustrating a
rolling mill;
Fig. 29 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 30 is a schematic front view illustrating a
rolling mill;
Fig. 31 is a diagrammatic view illustrating the
work rolls in shifted position;
Fig. 32 is a graph showing a variation of the
edge drop;
Fig. 33 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 34 is a graph showing an amount of occurred
edge drop;
Fig. 35 is a schematic front view illustrating a
rolling mill;
Fig. 36 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 37 is a schematic front view illustrating a
rolling mill;
Fig. 38 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;




~os~~5s
Fig. 39 is a schematic front view illustrating a
rolling mill;
Fig. 40 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 41 is a schematic front view illustrating a
rolling mill;
Fig. 42 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 43 is a schematic front view illustrating a
rolling mill;
Fig. 44 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 45 is a schematic front view illustrating a
rolling mill;
Fig. 46 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 47 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 48 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 49 is a schematic front view illustrating a
rolling mill;
Fig. 50 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fag. 51 is a schematic front view illustrating a
rolling mill;




-13-
~og~~5s
Fig. 52 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 53 is a schematic front view illustrating a
rolling mill;
Fig. 54 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets;
Fig. 55 is a schematic front view illustrating a
rolling mill; and
Fig. 56 is a graph showing a distribution of
sheet crown with respect to the number of rolled sheets.
The Best Mode for Carrying the Invention
This invention will be explained hereinafter on
the basis of examples shown in drawings.
Fig. 1 illustrates a six high rolling mill
according to the present invention.
Referring to Fig. 1, a housing 1 is provided
with pairs of upper and lower work rolls 2, intermediate
rolls 3 and backup rolls 4, respectively. The both work
rolls 2 are made capable of shifting in mutually
opposite direction toward each of the axial directions
thereof by means of shifting units 5 for each of them,
and the both intermediate rolls 3 are also made capable
of shitting in mutually opposite direction toward each
of the axial directions by means of other shifting units
6 for each of them.
Each of the backup rolls 4 is constituted by so-




2os~ms
called plain roll having a constant barrel diameter
throughout the entire length, and each of the
intermediate rolls 3 is constituted by a roll having a
barrel length longer than that of the backup roll and a
"S" shaped roll crown.
In this case, a forming curve of "S" shaped roll
crown may be selected from curves which are represented
by one pitch of a high order curve formed by a high
order function not lower than a third order function, a
sine curve and approximate curves of the high order
curve or the sine curve. It is preferred that the "S"
shaped roll crown to be applied for the intermediate
rolls has a difference between maximum and minimum roll
diameters not larger than 1 mm.
The intermediate rolls 3 with such a roll crown
are arranged in mutually opposite position as shown in
Fig. 1 and shifted in mutually opposite direction
between maximum and minimum shift positions shown in
Fig. 3(a) and (b) by means of shifting units 6.
In the minimum shift position shown in
Fig. 3(a), one barrel end 3a of the intermediate roll 3
is just aligned to one barrel end 4a of the backup roll 4,
while in the maximum shift position shown in Fig. 3(b)
the other barrel end 3b of the intermediate roll 3 is just
aligned to the other barrel end 4b of the backup roll 4.
As can be seen from Figs. 1 and 3, the work




_ i~ _
:rolls 2 are plain rolls having a constant diameter and
'the same barrel length as that of the barrel length of
the backup rolls.
Referring to Fig. 1, in the rolling mill with
rolls 2, 3 and 4 arranged as mentioned above, each of
the work rolls 2 is joined to a reduction gear 10
attached to a motor 9 successively through a spindle 7
and a pinion stand 8. In this case, the shifting
position of the work roll 2 by the shifting unit 5
joined to the work roll 2 through the spindle 7 and the
pinion stand 8 is detected by a position detecting unit
11 which can be, for example, a magnet scale, and the
shifting position of the intermediate roll 3 by the
shifting unit 6 joined to the intermediate roll 3 is
detected by another position detecting unit 12 which can
be also, for example, a magnet scale, respectively.
Incidentally, in the figure, 13, 14 and 15
indicate a rolled sheet as a product, a work roll bender
and an intermediate roll bender, respectively, and 16
indicates a load cell.
Fig. 4 is a diagrammatic view of a control
system of the rolling mill as described above.
In the figure, 21 indicates an arithmetic unit,
and into this arithmetic unit 21 are inputted beforehand
rolling conditions in one cycle such as a shape and a
size of the tapered portion of the work roll 2, a roll




-16-
~OS7~56
crown and size of the intermediate roll 3, a plate
width, a draft of each roll stand, a finish plate
thickness, a target sheet crown, a target sheet shape
and the like, and the arithmetic unit 21 calculates
setting values of a shifting amount of the intermediate
roll 3 and bending force of each of the roll benders 14
and 15 on the basis of such information and a cyclic
shifting amount of the work roll 2 in order to provide a
sheet crown and a sheet shape as the target.
And on the basis of the calculation result, each
of a shifting control unit 22 and a bender control unit
23 controls the operations of the shifting unit 6 and
the roll benders 14 and 15 there by each of the shifting
amount of the intermediate roll 3 and the roll bending
force is made as setting values to wait for the start of
rolling in such a state.
On the other hand, during the rolling, on the
basis of feedback signals from a sheet shape detecting
unit 24 and a plate crown detesting unit 25 to the
arithmetic unit 21, in order to realize the target sheet
shape and the target sheet crown with high accuracy, the
arithmetic unit 21 calculates corrected values of the
intermediate roll shifting amount and the roll bending
force. and the shifting control unit 22 and bender
control unit 23 adjust the shift amount of the
intermediate roll 3 and the bending force of the roll




2~8'~15~
benders 14, 15 in accordance with the correction values.
When rolling is carried out by the
aforementioned rolling mill, especially under the
function of the roll crown acting on the intermediate
roll 3, the rolling load given to the side edge portions
of a sheet bar from the work roll can be very
effectively lowered. Therefore, in addition to the
actions of the roll benders 14, 15, not only the sheet
crown can be controlled with high accuracy but by
shifting the intermediate roll 3, its control range can
be sufficiently extended.
Next, a method to give a roll crown to the
intermediate roll 3 will be explained, by way of an
example in which a roll crown is given in accordance
with an equation of the third order as shown in Fig. 2.
That is, the lower roll profile of the
intermediate roll 3 shown in Fig. 2(a) is the same as
the curve shown in Fig. 2(b), and this curve can be
expressed by the following equation (1).
2D y1(x) - -affx - (8 + OF)}/L]3 + b(x/L) ..... (1)
where y : generating line of the roll crown,
a . coefficient of the third order,
b : coefficient of the first order,
x . coordinate of the barrel center,
L . 1/2 of the barrel length of the intermediate
roll,




lg _
~1~~7156
8 : shift amount of the intermediate roll
(The start point is x = LB.), and
OF: offset amount in the axial direction.
On the other hand, the upger roll grofile of the
intermediate roll 3 being in point symmetry to the lower
roll profile with respect to a point can be expressed as
following equation (2).
y2(x) _ -of{x + (~ + OF)}/L]3 +b(x/L) ..... (2)
From the aforementioned equations (1) and (2), a
gap Dy between the upper and lower rolls is expressed by
the following equation.
2 2
Qy(X)_yl_y2_2.a_~8-~OF~~3~L) +Cs OF~ ~ ..... (3)
Composite roll crown CR formed by the upper and
lower intermediate rolls can be expressed by the
following equation (4), wherein the mill center is set
to be zero (0).
CR = Dy(O)- Dy(x) _ -6a{(8 + OF)/L}(x/L)2 ..... (4)
The maximum shift amount Amax to give the maximum
composite call crown can be expressed as follows.
Smax = L - LB ..... (5)
where LB: 1/2 of the barrel length of the backup roll.
In order to make the composite crown of the upper and
lower intermediate rolls to be zero when the shift
amount is the minimum value of 8min {_ -(L - La)~. the
offset amount OF must be as follows.




- 1 ~J -
2087i56
OF = L - LB ..... (6)
In a normal hot rolling process, the minimum
crown amount may be when the composite crown of the
upper and lower rolls is zero. However, when it is
necessary to make the minimum composite crown larger or
smaller than zero, offset amount OF using the position
where the shift amount of the intermediate roll is zero
(x = L) as a starting point, may be determined as
follows .
OF = C(L = LB)
where C is a constant.
In order to reduce difference between the
maximum and minimum diameters of the intermediate roll
without changing the composite roll crown, it is
effective to use the following equation obtained when
equations (S) and (6) are substituted for equation (4).
CR = -6a{(1 + C)(L - L~)/L3}~x3 ..... (8)
and to make the third order coefficient "a" to be
minimum, therefore to make (L - LB)/La to be maximum in
the aforementioned equation. In order to make (L - LB)jL~
to be maximum, the following equation is applied.
L = 1.5LH ..... (9)
Accordingly, when the barrel length of the
intermediate roll is made 1.5 times as long as that of
the backup roll, the maximum and minimum diameter
differences of the intermediate roll can be made small,




L~ .'
248~1~6
that is, when an S-shaped roll crown is formed on the
intermediate roll, the grinding amount can be reduced,
so that the life of the intermediate roll can be
lengthened in the process of~roll grinding.
Fig. 5 shows the result of a comparison of the
pressure distribution between rolls and the sheet crown
with a case using intermediate roll of L = 1.1LB.
As shown in Fig. 5, when the barrel length is 1.5LB
(solid line). the work roll is bent along the
intermediate roll, so that the sheet crown is reduced as
compared with a case in which the barrel crown is 1.1LB.
Also, as shown in Table 1, it is apparent that the
maximum pressure is smaller when the barrel length is
1.5LB, so that it contributes to improve the roll life.
Table 1
Length of Line pressure Line pressure


intermediate(kgf/mm) between(kgf/mm) between


intermediate intermediate
and and


roll backup rolls work rolls


1.5LB 911 986


1.1LB 1140 1155


[Experimental Example]
Next, the results of an experiment about an
intermediate roll especially barrel length will be
explained as follows.




_ 21 _
2os7~~s
That is the barrel length of a work roll used
was 2300 mm, its diameter was 680 mm, the barrel length
of a backup roll used was 2300 mm, and its diameter was
1330 mm. The barrel length of an intermediate roll was
variously changed in which the third order coefficient
"a" of equation (8) was 0.833. Sheet bars, having width
of 1500 mm and thickness of 5.2 mm, were rolled to the
thickness of 4.16 mm, and various investigations were
made.
First, Fig. 6 shows a relation between the ratio
(L/LH) of the intermediate and backup roll barrel
lengths, and the maximum pressure between the
intermediate and backup rolls. As shown in the drawing,
when the ratio (L/LB) is increased not less than
1.2 times, the pressure is gently lowered, so that it is
apparent that the intermediate roll of long barrel
length is favorable.
Fig. 7 shows a contact condition between the
intermediate and backup rolls with respect to a ratio of
barrel length under the condition that the same sheet
crown is obtained. As can be seen from Fig. 7, when the
ratio is increased not less than 1.2 times, the
occurrence of a noncontact region can be prevented, and
it is effective to improve the sheet thickness accuracy
and to inhibit the occurrence of meander and reduction
ears of sheet.




In general, when a gap is formed between a block
installed in a mill housing for shifting an intermediate
roll, and a chock of the intermediate roll (this gap is
formed due to abrasion caused by the slide of the
intermediate roll, and also due to defective accuracy of
the machine), a deflection is generated in the
intermediate roll 2 as shown in Fig. 8(a). Fig. 9 shows
a relation between the horizontal deflection amount t
and the ratio (L/LB) of barrel length of the
intermediate and backup rolls under the condition that
the aforementioned gap is 3 mm, wherein the maximum
displacement amount t between the chocks shown in
Fig. 8(b) is defined as the horizontal deflection
amount.
As shown in Fig. 9, the more the ratio is
increased, the more the horizontal deflection amount is
increased. When the horizontal deflection amount is
increased, a gap between the upper and lower work rolls
is changed, a gap between the upper and lower work rolls
is changed, and when the horizontal deflection amount of
the upper intermediate roll and that of the lower
intermediate roll becomes different, a roll gap between
the upper and lower work rolls becomes varied in the
axial direction, therefore the sheet crown and the sheet
profile fluctuate during the rolling operation.
For that reason, in order to reduce the barrel length




-23-
20~"~156
ratio, the intermediate roll length is preferred to be
short. Hocvever, in the case where the horizontal
bending amount is to the extent of 0.45 mm, it has
little influence on the sheet crown and profile, so that
it causes no problem in a normal rolling operation.
Further, the aforementioned gap is usually controlled to
be not more than 3 mm. Therefore, it is apparent that
when the barrel of the intermediate roll is not more
than 2.5 times as long as the backup roll, the rolling
can be carried out.
[Specific Example]
A comparative example will be explained as
follows in which a crown distribution with respect to
the number of rolled sheets and others were investigated
in a case using a rolling mill according to the present
invention and also in a case using a conventional
rolling mill.
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 1 were
arranged in three rolling stands in the rear stage,
sheet bars of 900 to 1600 mm width and 40 mm thickness,
were rolled to a low carbon steel thin sheet of 1.6 to
3.2 mm finished thickness, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.



-24-
In this caser the barrel length of the work
rolls as 2300 mm, that of the intermediate roll was
3450 mm, and that of the backup roll was 2300 mm. Also,
a difference between the maximum and minimum diameters
of the intermediate roll was 0.8 mm, and the inter-
mediate roll was shifted within a range from 0 mm to
700 mm.
Rolling Mill of the Prior Art
In a rolling mill train in which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backup rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet
crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig~ 10.
According to the results shown in Fig. 10, when
the ralling mill of the present invention was used, it is
apparent that a highly accurate sheet rolling operation
to obtain a sheet crown close to a target sheet crown
was able to be carried out even when the target crown
was changed. In this case, the rolling schedule with



-25-
2087156
respect to the sheet width of the rolling mill of the
present invention was set to be the same as that of the
rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 2 in the case where 100,000
tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill.
Table 2
Sheet thicknessFrequency


Average crownaccuracy of ears


(~'m) lQ (,um) (time)


Inventive 40 t46 2


rolling mill


Conventional 45 t60 11


rolling mill


In the rolling mill as described above, it is
preferable to supply lubricant to gaps between the
backup and intermediate rolls and/or the intermediate
and work rolls.
Referring to Fig. 11, lubricant supplying



- 26 -
~~0~715fi
nozzles 26 are arranged to direct lubricant from these
nozzles to a gap between the backup roll 4 and the
intermediate roll 3 and a gap between the intermediate
roll 3 and the work roll 2. The lubricant is supplied
to the lubricant supplying nozzles 26 through supply
pipes 29 from a lubricant tank 27 by means of a pump 28.
Furthermore, coolant is supplied to the intermediate
rolls 3 and the work rolls 2 from cooling nozzles 32
through coolant supply pipes 31 by means of a coolant
pump 30. The preferred lubricant is highly concentrated
emulsion of basic oil including a high pressure agent,
but when the lubricant is also used for cooling the rolls,
a lubricant having a low concentration may be used.
Referring to Fig. 12, the distance between the
lubricant supply nozzles 26 for the barrel portion
having large diameter of the intermediate roll 3 is
preferably smaller than that for the barrel portion
having small diameter to increase the supply amount of
lubricant. Instead of increasing of lubricant supply
amount, the concentration of the lubricant may be varied
in the axial direction of the intermediate roll to
obtain the same effect as mentioned above.
The rolling mill shown in Fig. 1 was used to
roll the sheet bars as mentioned above with use of
lubricant of 10~ emulsion and coolant of industrial
water in a manner as shown in Fig. 11 and at least 120




-2?-
~os~~~s
strips were rolled without occurring of roll seizure.
In comparison example using only industrial water as
coolant, the sheet bars were rolled in the same manner
as mentioned above with using only industrial water as
coolant, the roll seizure occurred on the work roll and
the intermediate roll when 100 strips have been rolled
and rolling operation was stopped.
In the rolling mill including the intermediate
roll provided with the roll crown, distribution of the
contact pressure between rolls is varied to vary the
bending of the work roll, thereby being possible to
control the sheet crown, therefor the shape of sheet.
Thus, the amount of crown control is not varied by the
change of rolling load. Accordingly, when the diameter
of the work roll is small, the deflection amount of the
center line of the work roll is greatly varied so that
the amount of crown control generated by,shifting the
intermediate roll becomes large. While, when the
diameter of the work roll is large, change in the
deflection amount of the center line of the work roll is
small so that the amount of crown control generated by
shifting the intermediate roll becomes small.
Results of test carried on rolled sheets of
1500 mm width with respect to the diameter of work roll
and the amount of crown control are shown in Fig. 13.
As can be seen from Fig. 13, when the diameter of the




_ ~g _
2og~r~5s
work roll is small, preferably not more than 700 mm, the
amount of crown control becomes large, but when the
diameter of the work roll is smaller than 400 mm, the
amount of horizontal bending of the work roll becomes
large and the roll profile becomes wrong so that the
work roll is difficult to be driven and the effect
caused by bending of the work roll is decreased.
Accordingly, the diameter of the work roll of at least
of 400 mm is desirable.
[Example 2)
Fig. 14 shows a rolling mill which is improved in
the mill rigidity by extending the roll barrel of the work
roll 2 to make its barrel length longer than that of the
intermediate roll 3 in the six high rolling mill shown in
Fig. 1. The mill rigidity of the rolling mill is deter-
mined by an amount of gap between work rolls when the
rolling load is changed. The amount of gap is influenced
by the deflection of the backup rolls, the elastic
deformation of the housing and others and the flat
deformation between rolls. When the barrel length of
the work roll is long and then the region contacting the
work roll and the intermediate roll is long. the mill
rigidity of the rolling mill is great since the contact-
ing pressure between rolls is smaller than that of the
case of a shorter contacting region even if the rolling
load is changed. Therefor, when the barrel length of



,u~
2087156
the work roll is long, even if the sheet passes in a
position deviated from the center of the rolling mill,
the variation in the pressure between rolls is small and
then the difference between the amounts of deformation
at the left and right side with respect to the center
line of the sheet is small. Accordingly the work roll
having a long roll barrel is effective for preventing
from meandering of sheet occurring of reduction ears.
It should be noted that a preferred range of the
barrel length is 1. 52.5 times as long as that of the
backup roll as described above, and a reason of such
limited range is substantially the same as the
aforementioned reason for the intermediate roll.
A comparative test will be explained in connec-
tion with a crown distribution with respect to the number
of rolled sheets and others which were investigated in a
case using the rolling mill according to this example
and also in a case using a conventional rolling mill.
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 14 were
arranged in three rolling stands in the rear stage, sheet
bars were rolled under the same conditions as in the
aforementioned Example 1, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel length of the work roll



2087156
was 3400 mm, that cf the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also, a
difference between the maximum and minimum diameters of
the intermediate roll was 0.8 mm. and the intermediate
roll was shifted within a range from 0 mm to 700 mm.
It is noted that a specification of the
conventional rolling mill used in this comparative test
is the same as in the case of the Example 1.
Results of Experiments
Results of measurement are shown in the graph of
Fig. I5. According to the results shown in Fig. 15,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 3 in the case where 100,000
tones of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of~the conventional rolling mill.




_gl_
2087i5fi
Table 3
Sheet Frequency


Average Crownthickness of ears


~~Cm) accuracy Mime)


ld (,um)


Inventive 45 tag 1


rolling mill


Conventional 50 t6p 11


rolling mill


In a cold rolling mill train consisting of four
rolling stands in which the six high rolling mills
structured as shown in Fig. 1 were arranged in the first
rolling stand, sheet bars of 900 to 1600 mm width and
2~3 mm thickness, were rolled to a low carbon steel thin
sheet of 1.6 to 0.5 mm finished thickness, and then the
sheet thickness deviation was investigated at a position
spaced from the edge by 100 mm.
In this case, the barrel length of the work roll
was 2000 mm, that of the intermediate roll was 2700 mm,
and that of the backup roll was 2000 mm. Also, a
difference between the maximum and minimum diameters of
the intermediate roll was 0.8 mm. and the intermediate
roll was shifted within a range from 0 mm to 700 mm.
Rollinct Mill of the Prior Art
A six high mill is arranged in the first rolling
stand and provided with work rolls, intermediate rolls
and backup rolls, all of them being plain'rolls and the
barrel length of them being 2000 mm while the



-32-
208716
intermediate rolls were being shifted, rolling
operations were carried out in the same manner as the
rolling mill of the invention, and the sheet thickness
deviation was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 16. According to the results shown in Fig. 16,
when the rolling mill of the present invention was used,
it is apparent that occurring of edge drop is reduced.
The frequency of occurring of reduction ears and
amount of edge drop are shown in Table 4 in the case
where 100,000 tons of sheets were rolled by use of the
aforementioned rolling mills of the invention and
conventional rolling mills. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the invention are far superior to those
of the conventional rolling mill. The amount of edge
drop is defined by thickness deviations at positions
spaced from the edge by 100 mm and 7.5 mm.
Table 4
Amount of edge drop Frequency of ears
(gym) (time)
Inventive 12 0
rolling mill
Conventional 15
rolling mill




-33-
~D87~.56
In case of applying the six high rolling mill
according to the present invention for cold rolling
sheet, in particular for controlling the edge drop in
the sheet, since deformation of the sheet in a direction
of sheet width decreases as the sheet passes through the
rear stands in the cold rolling mill train, the six high
rolling mill should be arranged in the first stand, and
preferably the six high rolling~mills are applied for
the rear stands in order from the first stand.
The strip sheet is subjected to a tension between the
stands of the cold rolling mill train so that the
meander of the sheet is restrained, but if the hot
rolled sheet has a large camber and wedge, the reduction
ear sometimes occurs owing to the camber and wedge.
In the rolling mill of the present invention, however
the intermediate roll has a long roll barrel to secure
the mill rigidity so that it is possible to prevent the
reduction ear from occurring in the sheet.
Next, a six high rolling mill including
intermediate rolls having a roll crown which is tapered
toward one end or both ends will be described.
[Example 4]
Fig. 17 illustrates a rolling mill having a
construction similar to the rolling mill shown in
Fig. l, except that each of intermediate rolls 3 has a
roll crown which is tapered toward one end of the roll


_g
~087~55
barrel. That is each of tine intermediate roll 3 has a
tapered barrel end portion 3a at mutually opposite side
and a plain barrel portion 3b extending over the greater
part of the barrel length from the tapered barrel end
portion a and having a constant diameter.
Furthermore, the roll barrel of each of the
intermediate roll 3 has such a barrel length that the
roll barrel contacts with the roll barrel of the backup
roll 4 over the full length thereof in the maximum
to shifted position of the intermediate roll and the
tapered barrel end portion 3a of the intermediate roll 3
extends beyond the barrel end of the backup roll 4 in no
shift position of the intermediate roll.
Under a rolling load, the tapered barrel end
portion 3a contacts with at least the backup roll 4,
usually both the work roll 2 and backup roll 4 even if
the work roll 2 is shifted to effectively reduce the
contact pressure between these rolls. Therefor, the
sheet crown can be controlled by appropriately selecting
20 positions contacting the tapered barrel end portion 3a
with the work roll 2 and the backup roll 4 by shifting
the intermediate roll 3, if necessary.
The contour shape of the tapered portion 3a of
the intermediate roll 3 may be made not only the tapered
shape shown in Fig. 17, but also a sine or~ cosine curve
shape as shown in Fig. 18(a), or a curve shape defined by




-35-
208'~L56
a, high order function such as second order, fourth order,
sixth order or more high order function as shown in
Fig. 18(b) depending on a required sheet crown, the maxi-
mum shift amount of the intermediate roll or the like.
In such a rolling mill, when the intermediate
roll 3 is shifted in point symmetry, for example, as
shown in Fig. 19, the contact pressure of the barrel
portion of each of the roll 2 and 4 which contacts with
the tapered portion 3a of the intermediate roll 3 can be
reduced extremely effectively, and owing to this fact,
in combination with the action of the roll benders 14
and 15, the plate crown can be optionally controlled
over a wide range.
Fig. 20 is a graph showing a distribution of
contact pressure between the upper side work roll 2 and
the intermediate roll 3r wherein in the contact state of
the both rolls 2 and 3, the pressure acting from the
intermediate roll 3 to the work roll 2 at the contact
portion of the work roll 2 with the tapered portion 3a
decreases as its diameter becomes small corresponding to
the tapered shape of the tapered portion 3a, which
becomes the smallest value at the barrel end of the work
roll 2. Therefore, the work roll 2 is curved into a
shape forming a convex form downwardly all over the roll,
the sheet crown of the sheet 13 is effectively reduced
as compared with a case in which the intermediate roll 3




-36-
~os~~5s
p.s not shifted.
Thus, according to this rolling mill, especially
the intermediate roll 3 has the length which is longer
than that of the backup roll 4, and even when the
intermediate roll 3 is shifted. the contact length of
the intermediate roll 3 between the backup roll 3 and
the intermediate roll 3 between the work roll 2 do not
change, and the mill rigidity of the rolling mill does
not change, so that the sheet thickness accuracy of the
hot finish rolling is greatly improved, and even when
the center of a sheet bar has deviated from the center
line of the rolling mill, the change in pressure at the
right and left side portions of the rolling mill becomes
smaller than that in the prior art, and the change in
roll flattening amount between rolls becomes small
further the sheet wedge becomes small, so that the
camber of the sheet can be effectively reduced.
Also in this case, even in a state in which the
intermediate roll 3 is not shifted at all. the tapered
port~.on 3a of the intermediate roll 3 contacts with the
barrel end portion of each of the work roll 2 and the
backup roll 4, so that the occurrence of the sheet crown
can be effectively reduced.
[Embodical example]
A comparative test will be explained herein-
after, in which a crown distribution with respect to the


-3?-
2U8'~:15fi
number of rolled sheets and others were investigated in
a case using a rolling mill according to the present
invention and also in a case using a conventional
rolling mill.
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 17 were
arranged in three rolling stands in the rear stage,
sheet bars of 900 to 1600 mm width and 40 mm thickness,
were rolled to a low carbon steel thin sheet of 1.6 to
3.2 mm finished thickness, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel lengths of the work
roll and backup roll were 2300 mm respectively, and that
of the intermediate roll was 3000 mm. Also, a tapered
portion of the intermediate roll was tapered by 1.6x10-3
(0.32 mm/200 mm per diameter), and the intermediate roll
was shifted within a range from 0 mm to 700 mm.
Rolling Mill of the Prior Art
In a rolling mill train 3.n which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backup rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,



-38-
20871~fi
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet
crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 21. According to the results shown in Fig. 21,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target sheet crown was changed. In this case, the
rolling schedule with respect to the sheet width of the
rolling mill of the present invention was set to be the
same as that of the rolling mill of the prior art.
The frequency of occurring reduction ears,
accuracy of sheet thickness, and average'value of sheet
crown are shown in Table 5 in the case where 100,000
tons of sheets were rolled. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the inventian are far superior to those
of the conventional rolling mill.



9_
~os7i5s
Table 5
Sheet Frequency


Average Crownthickness of ears


E2~ (,um) accuracy (time)


1Q (,um)


Inventive 44 43 5


rolling mill


Conventional 5p ~6p 12


rolling mill


[Example 5)
Fig. 22 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 17, except that
the barrel length of the work roll 2 is longer than that
of the intermediate roll 3.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rollina Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 22
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same condition as in
the aforementioned Example 4, and then the sheet crown
was measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel length of the work roll



_~0_
208715
was 3400 mm, that of the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also, the
intermediate roll is provided with the same taper shaped
crown as in the Example 4, and the intermediate roll was
shifted within a range from 0 mm to 700 mm. It is noted
that a specification of the conventional rolling mill
used in this comparative test is the same as in the case
of the Example 4.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 23. According to the results shown in Fig. 23,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 6 in the case where
100,000 tons of sheets were rolled by using the
aforementioned rolling mills of the invention and
conventional rolling mills. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the invention are far superior to those
of the conventional rolling mill.


_ ~i _
2p87i5~
Table 6
Sheet Frequency


Average Crownthickness of ears


E25 (,um) accuracy (time)


16 (gym)


Inventive 46 t36


rolling mill


Conventional50 X60 12


rolling mill


[Example 6]
Fig. 24 illustrates a rolling mill having a
construction similar to the rolling mill shown in
Fig. 1, except that each of intermediate rolls 3 has a
roll crown which is tapered from the center of the roll
barrel toward the opposite barrel ends. That is, each
of the intermediate rolls has a tapered end portion 3a
and a gently tapered end portion 3b to form an
asymmetric convex roll crown. Each of the intermediate
roll 3 has such a barrel length that the roll barrel
contacts with the roll barrel of the backup roll 4 over
the full length thereof in the maximum shifted position
of the intermediate roll.
Under a rolling load, the tapered portion 3a
contacts with at least the backup roll 4, usually, both
the work roll 2 and backup roll 4 even if the work roll
2 is shifted to effectively reduce the contact pressure
between these rolls. Therefor, the sheet crown can be
controlled by appropriately selected a position of a



~u -
~OS715~
boundary between the tapered portions 3a and 3b by
~;hifting the intermediate roll 3, if necessary.
The contour shape of the roll crown of the
intermediate roll may be made not only the tapered shape
shown in Fig. 24, but also a sine or cosine curve shape
as shown in Fig. 25(a) or a curve shape defined by a
high order function such as second order, fourth order,
sixth order or more high order function as shown in
Fig. 25(b) depending on a required sheet crown, the
maximum shift amount of the intermediate roll or the
like. Moreover, the contour shape of both the tapered
portions may be a similar shape or different shape.
In such a rolling mill, when the intermediate
roll 3 is shifted in point symmetry, for example, as
shown in Fig. 26, the contact pressure of the barrel
portion of each of the rolls 2 and 4 which contacts with
the tapered portions 3a and 3b of the intermediate roll
3 can be reduced extremely effectively, and owing to
this fact, in combination with the action of the roll
benders 14 and 15, the sheet crown can be optionally
controlled over a wide range, if necessary,
Particularly, in case of providing the roll
crown tapered toward the opposite ends of the roll
barrel, the boundary between the tapered portions 3a and
3b can coincide with the center in the axial direction
of the roll barrel of the backup roll 4 in the maximum




g_
~o~~i~s
shift position in which the barrel end 4a of the backup
roll 4 coincides with the barrel end 3c of the
intermediate roll 3 as shown in Fig. 26, thereby causing
the rigidity of the rolling mill in the axial direction
of the roll to make uniform.
A distribution of contact pressure between the
upper work roll 2 and the upper intermediate roll 3 in
this rolling mill is the same as that shown in Fig. 20,
that is, the pressure acting from the intermediate roll
3 to the work roll 2 at the contact portion of the work
roll 2 with the tapered portion 3a decreases as its
diameter becomes small corresponding to the tapered
shape of the tapered portion 3a, which becomes the
smallest value at the barrel end of the work roll 2.
Therefore, the work roll 2 is curved into a shape
forming a convex form downwardly all over the roll, and
the sheet crown of the sheet 13 is effectively reduced
as compared with a case in which the intermediate roll 3
is not shifted.
[Embodical Example]
A comparative test will be explained
hereinafter, in which a crown distribution with respect
to the number of rolled sheets and others were
investigated in a case using a rolling mill according to
the present invention and also in a case using a
conventional rolling mill.



20S'~~.~6
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 24 were
arranged in three rolling stands in the rear stage,
sheet bars of 900 to 1600 mm width and 40 mm thickness,
were rolled to a low carbon steel thin sheet of 1.6 to
3.2 mm finished thickness, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel lengths of the work
roll and backup roll were 2300 mm, respectively, and
that of the intermediate roll was 3000 mm. Also,
tapered portions 3a and 3b of the intermediate roll were
tapered by 1.6x10-3 (0.32 mm/200 mm per diameter) and
0.1x10-3 (0.02 mm/200 mm per diameter), respectively,
and the intermediate roll was shifted within a range
from 0 mm to 700 mm.
Rolling Mill of the Prior Art
In a rolling mill train in which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backup rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet




crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 27. According to the results shown in Fig. 2?,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target sheet crawn was changed. In this case, the
rolling schedule with respect to the sheet width of the
rolling mill of the present invention was set to be the
same as that of the rolling mill of the prior art.
The frequency of occurring reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 7 in the case where
100.000 tons of sheets were rolled. According to this
table, both the sheet thickness accuracy and the pass
property (decrease in the occurrence of reduction ears)
of the rolling mill of the invention are far superior to
those of the conventional rolling mill.
Table 7
Sheet Frequency


Average Crownthickness of ears


E25 (,um) accuracy (time)


16 (,um


Inventive 42 f40 4


rolling mill


Conventional 50 t60 12


rolling mill



2os~~5s
[Example 7J
Fig. 28 illustrates a rolling mill similar to
t:he six high rolling mill shown in Fig. 24, except that
the barrel length of the work roll 2 is longer than that
of the intermediate roll 3.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention an also
in a case using a conventional rolling mill.
Rollin2 -Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 28 were
arranged in three rolling stands in the rear stage, sheet
bars were rolled under the same condition as in the afore-
mentioned Example 1, and then the sheet crown was measured
every 5 coils at a position spaced from the edge by 25 mm.
In this case, the barrel length of the work roll
was 3400 mm, that of the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also, the
intermediate roll is provided with the same taper shaped
crown as in the Example 6, and the intermediate roll was
shifted within a range from 0 mm to 700 mm. It it noted
that a specification of the conventional rolling mill
used in this comparative test is the same as in the case
of the Example 6.




-4?-
2Q871~fi
Results of Experiments
Results of measurement are shown in the graph of
Fig. 29. According to the results shown in Fig. 29,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 8 in the case where
100,000 tons of sheets were rolled by using the
aforementioned rolling mills of the invention and
conventional rolling mills. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the invention are far superior to those
of the conventional rolling mill.
Table 8
Sheet Frequency


Average Crownthickness of ears


E25 (,um) accuracy (time)


la (,um)


Inventive 45 39 2


rolling mill


Conventional 50 t60 12


rolling mill





_~g_
2U8'~.~~6
Various rolling mills having roll crowns of "S"
shape, one end taper shape and both ends taper shape
iEormed on the intermediate roll have been described, but
various roll crowns can be combined as will be described
hereinafter.
[Example 8]
Fig. 30 illustrates a six high rolling mill in
which the intermediate rolls 3 are provided with the "S"
shape roll crowns, respectively, and the work rolls 2
are provided with the one end taper shape roll crowns,
respectively.
In this rolling mill, when the work rolls 2 are
shifted from positions shown in Fig. 31(a) to positions
shown in Fig. 31(b), respectively, roll gaps between the
tapered portions 2a of the upper and lower work rolls 2
are directly increased at both edge portions of the
sheet 13 to be rolled so that the edge drop can be
reduced. As can be seen from Fig. 32, the edge drop can
be modified by regulating a distance EL from the
starting point of the tapered portion 2a to the edge of
the sheet (referring to Fig. 31) so that the edge drop
can be controlled in accordance with a predetermined
target amount of edge drop.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets and others investigated in a case using a rolling




9_
2087156
mill according to the present invention and also in a
case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 30 were
axranged in three rolling stands in the rear stage,
sheet bars of 900 to 1600 mm width and 40 mm thickness,
were rolled to a low carbon steel thin sheet of 1.6 to
3.2 mm finished thickness, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel lengths of the work roll
and backup roll were 2300 mm respectively, and that of the
intermediate roll was 3000 mm. Also, a difference between
the maximum and minimum diameters of "S" shape roll crown
formed on the intermediate roll was 0.8 mm, the tapered
portion 2a of the work roll was tapered by a 8x10-3
(0.16 mm/200 mm per diameter) and the intermediate roll
was shifted within a range from 0 mm to 700 mm.
Rollina Mill of the Prior Art
In a rolling mill train in which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backup rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,



~087~.afi
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet
crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 33. According to the results shown in Fig. 33,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target sheet crown was changed. In this case, the
rolling schedule with respect to the sheet width of the
rolling mill of the present invention was set to be the
same as that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
amount of edge drop, accuracy of sheet thickness, and
average value of sheet crown are shown iri Table 9 in the
case where 100,000 tons of sheets were rolled.
According to this table, both the sheet thickness
accuracy and the pass property (decrease in the
occurrence of reduction ears) of the rolling mill of the
invention are far superior to those of the conventional
rolling mill. The amount of edge drop is measured by a
different between sheet thickness at positions spaced
Pram one sheet edge by 100 mm and 25 mm.




-51-
2o87i5~
Table 9
Average Sheet p~ount Frequency
thickness of


Crown edge dropof ears


E25 (gym)accuracy (gym) (time)


1Q (,um)


Inventive 38 f43 26 6


rolling mill


Conventional 50 t60 39 12


rolling mill


[Example 9]
In a cold rolling mill train consisting of four
rolling stands in which the six high rolling mills
structured as shown in Fig. 30 were arranged in the
first rolling stand, sheet bars of 900 to 1600 mm width
and 2~3 mm thickness, were rolled to a low carbon steel
thin sheet of 0.5 mm finished thickness, and then the
sheet thickness deviation was investigated at a position
spaced from the edge by 100 mm.
In this case, the barrel length of the work roll
was 2000 mm, that of the intermediate roll was 2700 mm,
and that of the backug roll was 2000 mm. Also, a
difference between the maximum and minimum diameters of
the intermediate roll was 0.8 mm, and the intermediate
roll was shifted within a range from 0 mm to 700 mm.
Rolling Mill of the Prior Art
A six high mill is arranged in the first rolling
stand and provided with work rolls, intermediate rolls
and backup rolls, all of them being plain rolls and the



_ J.~c.
208?15fi
barrel length of them being 2000 mm while the
intermediate rolls were being shifted, rolling
operations were carried out in the same manner as the
rolling mill of the invention, and the sheet thickness
deviation was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 34. According to the results shown in Fig. 34, when
the rolling mill of the present invention was used, it is
apparent that occurring of edge drop is greatly reduced.
The frequency of occurring of reduction ears and
amount of edge drop are shown in Table 10 ~in the case
where 100,000 tons of sheets were rolled by use of the
aforementioned rolling mills of the invention and
conventional rolling mills. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the invention far superior to those of
the conventional rolling mill.
Table 10
Amount of edge dropFrequency of
( ,um ) ears
( t ime )


Inventive 3 0


rolling mill


Conventional 15 3


rolling mill





-53-
20871~G
[Example 10)
Fig. 35 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 30, except that
each of the work rolls 2 is provided with a roll crown
tapered toward opposite ends.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 35 were
arranged in three rolling stands in the rear stage, sheet
bars were rolled under the same conditions as in the
aforementioned Example 8, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the opposite tapered barrel
portions 2a and 2b of the work roll were tapered by
0.4x10-3 (0.08 mm/200 mm per diameter). Also, a
difference between the maximum and minimum diameters of
the intermediate roll was 0.8 mm, and the intermediate
roll was shifted within a range from 0 mm to 700 mm.
It is noted that a specification of the conventional
rolling mill used in this comparative test is the same




_ a4 _
2U8715~
as in the case of the Example 8.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 36. According to the results shown in Fig. 36.
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 11 in the case where
100,000 tons of sheets were rolled in a thin cycle
rolling schedule using the aforementioned rolling mills
of the invention and conventional rolling mills. Accord-
ing tv this table, both the sheet thickness accuracy and
the pass property (decrease in the occurrence of
reduction ears) of the rolling mill of the invention are
far superior to those of the conventional rolling mill.
Table 11
Sheet
Average thickness fount Frequency
of


Crown edge drop of ears


E25 (/gym)accuracy (time)
(gym)


16 (gym)


Inventive 40 t40 28 7


rolling mill


Conventional 50 t60 39 12


rolling mill






-55-
(Example lI]
Fig. 37 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 35, except that
the barrel length of the work roll 2 is longer than that
of the intermediate roll 3.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 37
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same condition as in
the aforementioned Example 10, and then the sheet crown
was measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel length of the work roll
was 3900 mm, that of the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also, the
intermediate roll is provided with the same taper shaped
crown as in the Example 4, and the intermediate roll was
shifted within a range from 0 mm to 700 mm. It is noted
that a specification of the conventional rolling mill
used in this comparative test is the same as in the case


-5G-
2fl8'~~.56
of the Example 4.
Results of Extaeriments
Results of measurement for the sheet crown are
shown in the graph of Fig. 38. According to the results
shown in Fig. 38, when the rolling mill of the present
invention was used, it is apparent that a highly
accurate sheet rolling operation to obtain a sheet crown
extremely close to a target sheet crown was able to be
carried out even when the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 12 in the case where
100,000 tons of sheets were rolled by using the
aforementioned rolling mills of the invention and
conventional rolling mills. According to this table,
both the sheet thickness accuracy and the pass property
(decrease in the occurrence of reduction ears) of the
rolling mill of the invention are far superior to those
of the conventional rolling mill.
Table 12
Average Sheet fount of Frequency
thickness


Crown edge drop of ears


5 (gym) accuracy (gym) (time)


la (gym)


Inventive 41 42 25 5


rolling mill


Conventional 50 60 39 12


rolling mill





-5?-
2087156
[Example 12]
Fig. 39 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 37, except that
each of the work rolls 2 is provided with a roll crown
tapered toward opposite ends.
A comparative test was carried out in which a
crown distribution with respect to the number of rolled
sheets ar~d others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as~shown in Fig. 39
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same conditions as in
the aforementioned Example 11, and then the sheet crown
was measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the opposite tapered barrel
portions 2a and 2b of the work roll were tapered by
0.8x10-3 (0.16 mm/200 mm per diameter) and 0.01x10-3
{0.02 mm/200 mm per diameter), respectively, and the
intermediate roll was shifted within a range from 0 mm
to 700 mm. It is noted that a specification of the
conventional rolling mill used in this comparative test
is the same as in the case of the Example 11.



-58-
2087156
Results of Experiments
Results of measurement are shown in the graph of
Fig. 40. According to the results shown in Fig. 40,
when the rolling mill of the present invention was used,
it is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 13 in the case where
100,000 tons of sheets were rolled in a thin cycle
rolling schedule using the aforementioned rolling mills
of the invention and conventional rolling mills. Accord-
ing to this table, both the sheet thickness accuracy and
the pass property (decrease in the occurrence of
reduction ears) of the rolling mill of the invention are
far superior to those of the conventional rolling mill.
Table 13
Average Sheet Amount of Frequency
thickness


Crown edge drop of ears


5 (gym) accuracy (gym) (time)


ld (,um)


Inventive 40 t46 24 2


rolling mill


Conventional 45 t60 39 11


rolling mill





9_
X087156
[Example 13]
Fig. 41 illustrates an example of the six high
rolling mill, wherein each of the intermediate rolls 3
and the work rolls is provided with a roll crown tapered
toward one end of the roll barrel.
A comparative test is carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 41 were arranged
in three rolling stands in the rear stage, sheet bars of
900 to 1600 mm width and 40 mm thickness, were rolled to
a low carbon steel thin sheet of 1.6 to 3.2 mm finished
thickness, and then the sheet crown was measured every 5
coils at a position spaced from the edge by 25 mm.
In this case, the barrel lengths of the work
roll and backup roll were 2300 mm, and that of the
intermediate roll was 3000 mm. Also, the tapered
portion 3a of the intermediate roll is tapered by
1.6x10-3 (0.32 mm/200 mm per diameter) and the tapered
portion 2a of the work roll is tapered by 0.8x10-3
(0.16 mm/200 mm per diameter) and the intermediate roll
was shifted within a range from 0 mm to 700 mm:




-6U-
2087156
P~ollinq Mill of the Prior Art
In a rolling mill train in which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backup rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet
crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 42. According to the results shown in Fig. 42 when
the rolling mill of the present invention was used, it
is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed. In this case, the rolling
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 14 in the case where
100, 000 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the




-61-
2087.~~~
invention and conventional rolling mills. According to
this table. both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill.
Table 14
Average Sheet Amount Frequency
of


Crown thickness edge drop of ears


E25 (gym)accuracy (gym) (time)


la (,um)


Inventive 36 45 26 8


rolling mill


Conventional 50 t60 39 12


rolling mill


[Example 14]
Fig. 43 illustrates a rolling mill having a
construction similar to that of the six high rolling
mill shown in Fig. 41, except that each of the work
rolls is provided with a roll crown tapered at the
opposite end portions.
A comparative test is carried out in which a
crown distribution with respect to the number of rolled
sheets and others were investigated in a case using a
rolling mill according to the present invention and also
in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 43




2Q87i56
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same conditions as in the
Example 12, and then the sheet crown was measured every
coils at a position spaced from the edge by 25 mm.
In this case, the size of the rolls is the same
as that of the Example 14 and the shape of the inter-
mediate rolls is the same as that of the Example 13, but
the work roll 2 has tapered barrel portions 2a and 2b
tapered by 0.4x10-3 (0.8 mm/200 mm per diameter), and
the intermediate roll was shifted within a range from
0 mm to 700 mm. A specification of the conventional
rolling mill used in this comparative test is the same
as in the case of the Example 13.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 44. According to the results shown iri Fig. 44 when
the rolling mill of the present invention was used, it is
apparent that a highly accurate sheet rolling operation
to obtain a sheet crown extremely close to a target
sheet crown was able to be carried out even when the
target crown was changed. In this case, the rolling
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet


g_
2~87i56
crown are shown in Table 15 in the case where
100,000 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence or reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill.
Table 15
Sheet
Average Amount Frequency
thickness of


Crown edge dropof ears


E25 (gym)accuracy (gym) (time)


16 (,um)


Inventive 37 t47 27 7


rolling mill


Conventional 50 X60 39 12


rolling mill


[Experiment 15]
Fig. 45 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 41, except that
the barrel length of the work roll 2 is longer than that
of the intermediate roll 3.
A comparative test was carried out as follows in
which a sheet crown distribution with respect to the number
of rolled sheets and others were investigated in a case
using a rolling mill according to the present invention
and also in a case using a conventional rolling mill.




_ ~4
208'156
Rollinct Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 45
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same condition as in
the aforementioned Example 1. The sheet crown of rolled
sheet was measured every 5 coils at a position spaced
from the edge by 25 mm.
In this case, the barrel length of the work roll
was 3400 mm, that of the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also, each of
the intermediate and work rolls is provided with a roll
crown tapered toward one end of the roll barrel similar
to that of the Example 11, and the intermediate roll was
shifted within a range from 0 mm to 700 mm. It is noted
that a specification of the conventional rolling mill
used in this comparative test is the same as in the case
of Example 13.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 46. According to the results shown in Fig. 46 when
the rolling mill of the present invention was used, it
is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed. In this case, the rolling



2087156
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 16 in the case where
100,000 tons of sheets were rolled in a thin cycle
rolling schedule using the aforementioned rolling mills
of the invention and conventional rolling mills.
According to this table, both the sheet thickness
accuracy and the pass property (decrease in the
occurrence of reduction ears) of the rolling mill of the
invention are far superior to those of the conventional
rolling mill.
Table 16
Sheet
Average thicknessfount of Frequency


Crown edge drop of ears


E25 (fpm) accuracy (gym) (time)


la (,um)


Inventive 35 t46 22 3


rolling mill


Conventional 50 f60 39 12


rolling mill


[Example 16]
Fig. 47 illustrates a rolling mill having a
construction similar to that of the six high rolling
mill shown in Fig. 43, except that each of the work




_ ~(~ _
2Q~'~156
rolls is provided with a roll crown tapered at the
opposite end portions thereof.
A comparative test is carried out in which a
sheet crown distribution with respect to the number of
rolled sheets and others were investigated in a case
using a rolling mill according to the present invention
and also in a case using a conventional rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 47
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same conditions as in
the Example 13, and then the sheet crown was measured
every 5 coils at a position spaced from the edge by
25 mm.
In this case, the size and shape of the rolls
are the same as those of the Example 15 and the work
roll 2 has tapered barrel portions 2a and 2b tapered by
0,8x10-3 (0.16 mm/200 mm per diameter) and 0.1x10-3
(0.02 mm/200 mm per diameter), respectively.
The intermediate roll was shifted within a range from
0 mm to 700 mm. A specification of the conventional
rolling mill used in this comparative test is the same
as those in the case of the Example 13.
Results of Experiments
Results of measurement of the sheet crown are




-6?-
2~8715fi
shown in the graph of Fig. 48. According to the results
shown in Fig. 48 when the rolling mill of the present
invention was used, it is apparent that a highly
accurate sheet rolling operation to obtain a sheet crown
extremely close to a target sheet crown was able to be
carried out even when the target crown was changed.
Tn this case, the rolling schedule with respect to the
sheet width of the rolling mill of the present invention
was set to be the same as that of the rolling mill of
the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 1? in the case where
100,00 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill,
Table 17
Average Sheet Amount Frequency
thickness of


Crown edge drop of ears


E25 ( accuracy (gym) (time)
um)


, la (/.cm)


Inventive 3g 45 26 4


rolling mill


Conventional 50 t60 39 12


rolling mill





_ ~$ _
[:Example 17]
Fig. 49 illustrates an embodiment of the six
high rolling mill having intermediate rolls 3 provided
with the roll crown tapered toward to the opposite ends
of the roll barrel and work rolls 2 provided with the
roll crown tapered at ane end portion of the roll barrel.
A comparative test was carried out as follows in
which a sheet crown distribution with respect to the
number of rolled sheets anal others were investigated in
a case using a rolling mill according to the present
invention and also in a case using a conventional
rolling mill.
Rolling Mill of the Present Invention
In a rolling mill train in which the six high
rolling mills structured as shown in Fig. 49 were
arranged in three rolling stands in the rear stage,
sheet bars of 900 to 1600 mm width and 40 mm thickness,
were rolled to a low carbon steel thin sheet of 1.6 to
3.2 mm finished thickness, and then the sheet crown was
measured every 5 coils at a position spaced from the
edge by 25 mm.
In this case, the barrel length of the work roll
was 2300 mm, that of the intermediate rolls as 3000 mm,
and that of the backup roll was 2300 mm. Also, the
tapered portion 3a and 3b of the roll barrel of the inter-
mediate roll are tapered by 1.6x10-3 (0.32 mm/200 mm per



_ g9 _
i~iameter) and 0.1x10-3 (0.02 mm/200 mm per diameter),
respectively, and the tapered portion 2a of the roll
barrel of the work roll is tapered by 0.8x10-3
(0.16 mm/200 mm per diameter). The intermediate roll
was shifted within a range from 0 rnm to 700 mm.
Rolling Mill of the Prior Art
In a rolling mill train in which six high mills
were arranged in three rolling stands in the rear stage
including the final rolling stand, provided with work
rolls, intermediate rolls and backug rolls, all of them
being plain rolls and the barrel length of them being
2300 mm while the intermediate rolls were being shifted,
rolling operations were carried out in the same manner
as the rolling mill of the invention, and the sheet
crown was measured in the same manner.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 50. According to the results shown in Fig. 50 when
the rolling mill of the present invention was used, it
is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed. In this case, the rolling
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.



-70
~~g7~~6
the frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 18 in the case where
100, 000 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill.
Table 18
Average Sheet fount of Frequency


Crown thickness edge drop of ears


E25 (;um)accuracy (gym) (time)


la (,um)


Inventive 39 t49 23 7


rolling mill


Conventional 50 t60 39 12


rolling mill


[Experiment 18]
Fig. 51 illustrates a rolling mill having a
construction similar to that of the six high rolling
mill shown in Fig. 49, except that each of the work
rolls 2 is provided with a roll crown tapered at the
opposite end portions.
A comparative test was carried out as follows in
which a sheet crown distribution with respect to the



20g i~~5fi
number of rolled sheets and others were investigated in
a case using a rolling mill according to the present
invention and also in a case using a conventional
rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 51
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same conditions as in
the Example 17, and then the sheet crown was measured
very 5 coils at a position spaced from the edge by 25 mm.
In this case, the tapered portions 3a and 3b of
the intermediate roll 3 and the tapered portion 2a of
the work roll are tapered similarly as in the afore-
mentioned Example 17 and the other tapered portion 2b of
the work roll 2 is tapered by 0.4x10-3 (0.08 mm/200 mm
per diameter). The intermediate roll was shifted within
a range from 0 mm to 700 mm. A specification of the
conventional rolling mill used in this comparative teat
is the same as in the case of the Example 17.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 52. According to the results shown in Fig. 52 when
the rolling mill of the present invention was used, it
is apparent that a high accurate sheet rolling operation
to obtain a sheet crown extremely close to a target




_?~_
~o~~~~s
sheet crown was able to be carried out even when the
target crown was changed. In this case, the rolling
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 19 in the case where
100, 000 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears) of the rolling mill of the invention are far
superior to those of the conventional rolling mill.
Table 19
Average Sheet fount of Frequency
thickness


Crown edge drop of ears


(gym) accuracy (gym) (time)


la (,um)


Inventive 35 t46 26 9


rolling mill


Conventional 50 t60 39. 12


rolling mill


[Example 19]
Fig. 53 illustrates a rolling mill similar to
the six high rolling mill shown in Fig. 49, except that




-73-
~087i5fi
the barrel length o~ the work roll 2 is longer than that
of the intermediate roll 3.
A comparative test was carried out as follows in
which a sheet crown distribution with respect to the
number of rolled sheets and others were investigated in
a case using a rolling mill according to the present
invention and also in a case using a conventional
rolling mill.
Rolling Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 53
were arranged in three rolling stands in the rear stage,
sheet bars were rolled under the same condition as in
the aforementioned Example 17. The sheet crown of
rolled sheet was measured every 5 coils at a position
spaced from the edge by 25 mm.
In this case, the barrel length of the work roll
was 3400 mm, that of the intermediate roll was 3000 mm,
and that of the backup roll was 2300 mm. Also. each of
the intermediate rolls is provided with a roll crown
tapered toward opposite ends of the roll barrel similar
to that of the Example 17 and each of the work rolls is
provided with a roll crown tapered toward one end of the
roll barrel similar to that of the Example 17.
The intermediate roll was shifted within a range from
0 mm to 700 mm. It is noted that a specification of the




2os7i5s
conventional rolling mill used in this comparative test
is the same as that in the case of Example.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 54. According to the results shown in Fig. 54 when
the rolling mill of the present invention was used, it
is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed. In this case, the rolling
schedule with respect to the sheet width of the rolling
mill of the present invention was set to be the same as
that of the rolling mill of the prior art.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 20 in the case where
100,000 tons of sheets were rolled in a thin cycle
rolling schedule using the aforementioned rolling mills
of the invention and conventional rolling mills.
According to this table, both the sheet thickness
accuracy and the pass property (decrease in the
occurrence of reduction ears) of the rolling mill of the
invention are far superior to those of the conventional
rolling mill.



-?5-
2U87156
Table 20
Average Sheet p~ount Frequency
thickness of


Crown edge drop of ears


E25 ( accuracy (~) (time)
um)


, la (gym)


Inventive 3g t49 22 5


rolling mill


'Conventional50 f60 39 12


rolling mill


[Example 20]
Fig. 55 illustrates a rolling mill having a
construction similar to that of the six high rolling
mill shown in Fig. 51, except that each of the work
rolls is provided with a roll crown tapered at the
opposite end portions thereof.
A comparative test is carried out in which a
sheet crown distribution with respect to the number of
rolled sheets and others were investigated in a case
using a rolling mill according to the present invention
and also in a case using a conventional rolling mill.
Rollinct Mill of the Present Invention
In a hot finish rolling mill train in which the
six high rolling mills structured as shown in Fig. 55 were
arranged in three rolling stands in the rear stage, sheet
bars were rolled under the same conditions as in the
Example 17. The sheet crown of rolled sheet was measured
every 5 coils at a position spaced from the edge by 25 mm.
In this case, the size and shape of the



-~6-
~os~i~s
intermediate rolls are the same as those of the Example
19 and the work roll 2 has tapered barrel portions 2a
and 2b tapered by 0.8x10-3 (0.16 mm/200 mm per diameter)
and 0.1x10-3 (0.02 mm/200 mm per diameter),
respectively. The intermediate roll was shifted within
a range from 0 mm to 700 mm. A specification of the
conventional rolling mill used in this comparative test
is the same as those in the case of the Example 17.
Results of Experiments
Results of measurement are shown in the graph of
Fig. 56. According to the results shown in Fig. 56 when
the rolling mill of the present invention was used, it
is apparent that a highly accurate sheet rolling
operation to obtain a sheet crown extremely close to a
target sheet crown was able to be carried out even when
the target crown was changed.
The frequency of occurring of reduction ears,
accuracy of sheet thickness, and average value of sheet
crown are shown in Table 21 in the case where
100,000 tons of sheets were rolled in a thin cycle rolling
schedule using the aforementioned rolling mills of the
invention and conventional rolling mills. According to
this table, both the sheet thickness accuracy and the
pass property (decrease in the occurrence of reduction
ears of the rolling mill of the invention are far
superior to those of the conventional rolling mill.




208756
Table 21
Average Sheet fount of Frequency


Crown thickness edge drop of ears


(gym) accuracy (gym) (time)


la (,um)


Inventive 35 t,~6 26 7


rolling mill


Conventional 50 t60 39 12


rolling mill


Industrial Utilizability
According to the present invention, rolled
sheets having a target sheet shape of desired sheet
crown and edge drop can be rolled in high accuracy.
Thus, the yield in the after process can be improved and
the rolling operation can be carried out in stable
condition. Furthermore, the life of intermediate roll
and the work roll can be improved.

Representative Drawing